According to China’s grid connection standards

the topological structure

operation method

flow level and direction of distribution network will be complicated and changeable because medium and small capacity inverter-interfaced distributed generators（IIDGs） are connected

which will pose a great challenge to the protection of active distribution networks. Consequently

we analyze the characteristics of positive-sequence currents fault component in active distribution networks in detail after taking the IIDG low-voltage ride-through capacity with PQ control strategy into account

and propose a pilot protection scheme based on fault components. The scheme can be adopted to reduce the synchronous sampling requirement of the pilot protection for communication equipment and eliminate the influence of load current through the transmission of fault component amplitude

which will greatly improve the protection performance. At the same time

the existence of un-measurable branch of the feeder may cause incorrect operation of the pilot protection criterion about amplitude comparison in non-fault line

therefore

an node branch current sudden-change auxiliary criterion is established according to the fault characteristics at the node branch through distribution system side

which can be adopted to effectively solve the action blind area of protection criterion. Finally

the feasibility of the proposed protection principle is verified by the simulation of DIgSILENT.